I have no personal interest in knowing the actual values of the capacitors as I'm not going to modify the original circuit anyway. But for those who want to do component swaps, it would help to know the original values and also dielectric material. My personal interest consists only of knowing the circuit on a conceptual level.
I recognize the grounding issue you mentioned and I too am looking for commercially available spring contacts which can be used. The concept you describe is used in Neumann SDC, e.g. the KM184. You can see the internals here:??. I was thinking of using nickel-plated steel tags used for batteries. But the ones I could find are actually pure nickel and too soft. I know Nickel plated stainless steel tags do exist (they are used in my company's rechargeable products), but I haven't been able to get hold of them in the right dimensions on e.g. Aliexpress. So for the time being, my best option is this:??. You may want to clip the + terminal. The two "ears" of the CR2032 battery retainer push against the inside of the mic tube. Haven't tried it yet. Is anyone having a better idea?
Alternatively, at the XLR side, the pin 1 connection to the tube can als be established by using an XLR connector with an integrated grounding tab. I use these:??. They slip nicely into the tube and instead of a single, questionable ground connection to the tube, you'll get a double connection. Btw, due to the thicknes of the solder cups of this connector, only 1mm or 1.2mm PCBs will fit. You cannot push a 1.6mm PCB into the space between the pins. Other XLR connectors might accept 1.6mm PCBs, but not this one. For 1.6mm PCBs, consider these:??. But these are without grounding tabs.
Another thing to think about when using 1.6mm PCBs is the following: When you insert/pull the PCBA into/from the tube, then in my experience you'll have to bend the PCB somewhat in the switches area by pushing on the switches. This might prove to be a little (too) difficult with 1.6mm PCBs. I don't know, just guessing...
I once tried to screw Rode NT5 capsules on my SC140. The thread is indeed slightly different and you'll not be able to screw it all the way down to the end stop. It would have been nice if one could have other capsules than the Cardioid capsule on the SC140, which would make it a universal, cheap workhorse SDC. So I mailed 797 Audio with a request for Omni and HAC capsules which would fit on the SC140, but never received an answer. I even mailed them for a 2nd time but to no avail. While others seem to be successful in contacting 797 and even sourcing capsules from them directly, 797 Audio didn't care to reply :-(. Maybe someone else would like to give it a try and maybe we can do a group buy? Seems they take customer orders for at least 100 pcs. Will be difficult to reach such high numbers in a group buy, but who knows...
PS, I thought I introduced myself back in 2021 when I signed up for Groups.io. However, I didn't but will do so later.
Jan
